Hand strapping tools are conventionally used to apply strapping material, made of either plastic, steel, or similar materials, around various articles, packages, or loads. In operating such a conventional hand strapping tool, the feed wheel, which is an element or component of the tool tensioning unit, is driven by a suitable motor drive and serves to tension the strapping material to a predetermined amount of tension as determined by stalling of the motor when the predetermined amount of tension level is attained. Subsequently, the strapping is joined and severed and a new article, package, load, or the like is readied for a strapping operation. As a result of such multiple strapping operations involving such tensioning processes, feed wheels undergo wear and therefore need to be replaced. However, with conventional hand strapping tools, the replacement of the feed wheel is not especially convenient and is quite time-consuming as can be better appreciated as a result of reference being made to FIGS. 1 and 2 of the drawings.
FIGS. 1 and 2 disclose a conventional hand strapping tool which is generally indicated by the reference character 10. Briefly, the hand strapping tool 10 comprises a tension unit 12 which includes a motor drive, not shown, and a gearbox 14 operatively connected to the tension unit motor drive. An output feedwheel shaft 16 projects laterally outwardly from one side of the gearbox portion 14 of the tension unit 12, and a portion of the external periphery of the feedwheel shaft 16 has a hexagonal configuration. A feedwheel 18, having a complementary internal hexagonal peripheral surface, is adapted to be mounted upon the feedwheel shaft 16 so as to be driven by the feedwheel shaft 16 as a result of the driving force generated by the tension unit motor drive and transmitted by the gearbox 14. The feedwheel shaft 16 passes through an aperture 19 of a breaker foot 20, and the feedwheel 18 is maintained upon the outer or distal end of the feedwheel shaft 16 by means of an outer link 22, the outer link 22 also being provided with an aperture 23 through which the free or distal end of the feedwheel shaft 16 passes. The outer link 22 is in turn mounted upon a position link 24 by means of a pin 26, wherein the position link 24 and pin 26 comprise a sub-assembly. Position link 24 is mounted upon a support rod 28 through means of another pin 30. A hanger rod 32, as shown in FIG. 2, has casting flanges or mounting brackets 34, only one of which is shown in FIG. 2, mounted thereon upon respective opposite sides of the tool.
The tension unit 12, the feedwheel assembly comprising the feedwheel shaft 16 and the feedwheel 18, and the outer link 22 are mounted upon casting flanges 34 through means of a pivot shaft 36 and a nut 38. The pivot shaft 36 and nut 38 permit the tension unit 12, the feedwheel assembly comprising the feedwheel shaft 16 and the feedwheel 18, and the outer link 22 to be pivotally movable between operative and inoperative positions with respect to upper and lower straps which are to be tensioned and joined together and which are shown at 42 and 44 respectively. The pivot shaft 36 is seen to extend or pass through apertures 37,39, 41, and 43 respectively provided within the casting flange 34, outer link 22, breaker foot 20, and the gearbox portion 14 of the tension unit 12. The motor drive of the tension unit 12 is activated by means of a manual trigger lever 40.
It can thus be appreciated that when the feedwheel 18 needs to be replaced, the pivot shaft 36 must first be removed from the tool 10 whereby the entire tension unit assembly comprising the tension unit 12, the feedwheel shaft 16 and feedwheel 18, and the outer link 22 are disengaged and able to be removed from the casting flanges 34. The outer link 22 and the pin 26 must then be removed as a sub-assembly from the position link 24 whereby access to the feedwheel 18 upon the feedwheel shaft 16 is then achieved such that the worn feedwheel 18 can now be replaced. Once the new feedwheel has been placed upon the feedwheel shaft 16, the reverse procedures concerning the disposition or mounting of the outer link 22 and pin 26 upon the position link 24, as well as the disposition or mounting of the entire tension unit assembly upon the casting flanges 34 by means of the pivot shaft 36, must then be performed. It can therefore be appreciated that replacement procedures with respect to the feedwheel 18, comprising the disassembly of the tool component parts, and the re-assembly of such parts, as noted hereinabove, can be quite time-consuming.
A need therefore exists in the art for a hand strapping tool wherein the structural assembly of the tension unit, and in particular, the mounting of the feedwheel thereon, is such that replacement of the feedwheel as necessary due to wear or other conditions, is considerably simplified in order to render the replacement procedure for the feedwheel relatively easy, straightforward, and quick with minimum production downtime.